The rapid growth of space-based services has established Low Earth Orbit (LEO) satellite networks as a promising option for global broadband connectivity. Next-generation LEO networks leverage inter-satellite links (ISLs) to provide faster and more reliable communications compared to traditional bent-pipe architectures, even in remote regions. However, the high mobility of satellites, dynamic traffic patterns, and potential link failures pose significant challenges for efficient and resilient routing. To address these challenges, we model the LEO satellite network as a time-varying graph comprising a constellation of satellites and ground stations. Our objective is to minimize a weighted sum of average delay and packet drop rate. Each satellite independently decides how to distribute its incoming traffic to neighboring nodes in real time. Given the infeasibility of finding optimal solutions at scale, due to the exponential growth of routing options and uncertainties in link capacities, we propose SKYLINK, a novel fully distributed learning strategy for link management in LEO satellite networks. SKYLINK enables each satellite to adapt to the time-varying network conditions, ensuring real-time responsiveness, scalability to millions of users, and resilience to network failures, while maintaining low communication overhead and computational complexity. To support the evaluation of SKYLINK at global scale, we develop a new simulator for large-scale LEO satellite networks. For 25.4 million users, SKYLINK reduces the weighted sum of average delay and drop rate by 29% compared to the bent-pipe approach, and by 92% compared to Dijkstra. It lowers drop rates by 95% relative to k-shortest paths, 99% relative to Dijkstra, and 74% compared to the bent-pipe baseline, while achieving up to 46% higher throughput. At the same time, SKYLINK maintains constant computational complexity with respect to constellation size.

Radiation shock waves from solar activities are known to be a menace to spaceborne electronic infrastructure. Recent deployments, like the SpaceX Starlink broadband mega-constellation, open up the possibility to measure such impact on Low Earth Orbit infrastructure at scale. Our tool, CosmicDance, enables a data-driven understanding of satellite orbital shifts due to solar radiations. CosmicDance could also signal corner cases, like premature orbital decay, that could lead to service holes in such globally spanning connectivity infrastructure. Our measurements with CosmicDance show that Starlink satellites experience both short and long-term orbital decay even after mild and moderate intensity solar events, often trespassing neighboring shells of satellites.

Network measurement has long focused on the bits and bytes --- low-level network metrics such as latency and throughput, which have the advantage of being objective and directly characterizing the performance of the network. We argue that users provide a rich and largely untapped source of implicit as well as explicit signals that could complement and expand the coverage of traditional methods. Implicit feedback leverages user actions to indirectly infer the network performance and the resulting quality of user experience. Explicit feedback leverages user input, typically provided offline, to expand the reach of network measurement, especially for newer ones.

Interactive networked applications require high throughput, low latency, and high reliability from the network to provide a seamless user experience. While meeting these three requirements simultaneously is difficult, there has been an emergence of heterogeneous virtual channels (HVCs) which support some subset of them at the expense of the others. For instance, URLLC sacrifices throughput to achieve low latency and reliability in 5G NR, and Wi-Fi 7 and other novel Internet architectures provide similar disparate types of service. Prior work either focuses on aggregating the bandwidth of these channels whilst neglecting their unique properties or fails to generalize in the sense of achieving high performance across different applications and channels. To utilize HVCs to their fullest, we argue that there are challenges and opportunities across the network, transport and application layers, and the application-transport interface of the network stack. In this work, we explore the trade-offs of these architectural choices in the context of web browsing and real-time video, and identify the constituting principles of a design that is general, performant, and deployable.

Space industry upstarts are deploying thousands of satellites to offer global Internet service. These plans promise large improvements in coverage and latency, and could fundamentally transform the Internet. But what if this transformation extends beyond network transit into a new type of computing service? What if each satellite, in addition to serving as a network router, also offers cloud-like compute, making the new constellations not just global Internet service providers, but at the same time, a new breed of cloud providers offering "compute where you need it"?

Buoyed by advances in space technology, several firms are planning satellite constellations to offer broadband Internet service. While these developments are happening quickly, there are also many uncertainties about the design of these networks. A key open question is whether or not they will incorporate direct connectivity between satellites, instead of only ground-satellite connections. We compare the network behavior resulting from the two outcomes of that question. Our analysis shows that inter-satellite links substantially reduce the temporal variations in latency, add greater resilience to weather, and could yield more than 3x the throughput achieved without such links. Thus, whether this one design element pans out could have a large bearing on the performance, reliability, and economics of these networks.

Low latency is of interest for a variety of applications. The most stringent latency requirements arise in financial trading, where sub-microsecond differences matter. As a result, firms in the financial technology sector are pushing networking technology to its limits, giving a peek into the future of consumer-grade terrestrial microwave networks. Here, we explore the world's most competitive network design race, which has played out over the past decade on the Chicago-New Jersey trading corridor. We systematically reconstruct licensed financial trading networks from publicly available information, and examine their latency, path redundancy, wireless link lengths, and operating frequencies.

SpaceX, Amazon, and others plan to put thousands of satellites in low Earth orbit to provide global low-latency broadband Internet. SpaceX's plans have matured quickly, such that their underdeployment satellite constellation is already the largest in history, and may start offering service in 2020.

Upstart space companies are actively developing massive constellations of low-flying satellites to provide global Internet service. We examine the problem of designing the inter-satellite network for low latency and high capacity. We posit that the high density of these new constellations and the high-velocity nature of such systems render traditional approaches for network design ineffective, motivating new methods specialized for this problem setting.

Hackers hide behind compromised intermediate hosts and pose advanced persistent threats (APTs). The compromised hosts are used as stepping stones to launch real attacks, as is evident from an incident that shook the world in 2016 - Panama Papers Leak. The major attack would not go unnoticed if the compromised stepping stone, in this case an email server, could be identified in time. In this paper, we explore how today's programmable networks could be retrofitted with effective stepping stone detection mechanisms to correlate flows. We share initial results to prove that such a setup exists. Lastly, we analyze scalability issues associated with the setup and explore recent developments in network monitoring which have potential to address these issues.

A new space race is imminent, with several industry players working towards satellite-based Internet connectivity. While satellite networks are not themselves new, these recent proposals are aimed at orders of magnitude higher bandwidth and much lower latency, with constellations planned to comprise thousands of satellites. These are not merely far future plans --- the first satellite launches have already commenced, and substantial planned capacity has already been sold. It is thus critical that networking researchers engage actively with this research space, instead of missing what may be one of the most significant modern developments in networking.